Cathode active material comprising additive for improving overdischarge-performance and lithium secondary battery using the same

a lithium secondary battery and active material technology, applied in the field can solve the problems of reducing the capacity affecting the performance of lithium secondary batteries, so as to achieve the effect of not significantly reducing the cell capacity

Inactive Publication Date: 2007-01-18
LG CHEM LTD
View PDF2 Cites 34 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0010] The present inventors tried to develop a cell, in which by using a lithium manganese oxide having a layered structure,

Problems solved by technology

However, a lithium secondary cell may ignite and explode due to extreme heat emission, when it is over-charged or is in a short circuit state.
Moreover, when a lithium secondary cell is over-discharged below a normal voltage range, its capacity is rapidly reduced so that it may not be used any more.
However, such protection circuits, PTCs, etc., are not preferable, because they are expensive and take up a large volume, thereby increasing the price, volume and weight of the cell.
However, in the case that a cell is over-discharged below an adequate voltage, even if one tries to charge the cell again, the cell capacity is so rapidly reduced that charge/discharge of the cell may not be accomplished any more.
Thus, the copper foil is dissolved in a copper ion state, contaminating electrolytes, is attached again to the surface of the anode during re-charge, and thus the anode active material becomes unus

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Cathode active material comprising additive for improving overdischarge-performance and lithium secondary battery using the same
  • Cathode active material comprising additive for improving overdischarge-performance and lithium secondary battery using the same
  • Cathode active material comprising additive for improving overdischarge-performance and lithium secondary battery using the same

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0049] A pouch-type polymer cell of 383562 size was manufactured by a conventional method.

[0050] LiCoO2 was used as a cathode active material and LiCr0.1Mn0.9O2 was added in the amount of 8 parts by weight based on 100 parts by weight of the cathode active material.

[0051] LiCr0.1Mn0.9O2 was prepared by mixing lithium carbonate, manganese oxide and chrome oxide in solid phases, heat-treating the mixture at a temperature of 1000° C. under argon atmosphere for 12 hours, pulverizing the heat-treated mixture and further heat-treating the pulverized mixture at a temperature of 1100° C. under argon atmosphere for 12 hours.

[0052] Additionally, Super-p and PVDF polymer, used as a conductive agent and a binder, respectively, were added to NMP as a solvent to form cathode mixture slurry, and then the slurry was coated on an Al collector to obtain a cathode. On the other hand, artificial graphite and copper were used as an anode active material and an anode collector, respectively, and an EC...

experimental example 1

[0054]FIG. 3 is a graph showing the result of a structural analysis of the lithium manganese oxide, LiCr0.1Mn0.9O2, used as an additive for a cathode active material in Example 1 by X-ray diffraction. According to FIG. 3, it is apparent that the lithium manganese oxide of formula 1 is a compound having a layered structure.

[0055] On the other hand, as shown in FIG. 4, the lithium manganese oxide having a layered structure, LiCr0.1Mn0.9O2, was structurally changed into a spinel structure, after a coin-type cell obtained by using the same compound as an additive for a cathode active material experienced initial charge / discharge.

[0056] Additionally, as demonstrated in FIG. 5 showing the first charge / discharge capacity of a coin-type cell obtained by using the lithium manganese oxide of formula 1 having a layered structure as an additive for a cathode active material, the cell provided a very low first charge / discharge efficiency. As demonstrated in FIG. 6 showing the charge capacity a...

experimental example 2

[0057] A charge capacity and a discharge capacity before and after an over-discharge test were determined using each of the pouch-type polymer cells of 383562 size obtained from Example 1 and Comparative Example 1, through a conventional method. The over-discharge test results are shown in FIG. 8. Each of the numbers means a discharge capacity restorability at 0.2C and 1C after over-discharge, based on a discharge capacity at 0.2 C and 1 C before over-discharge. As shown in FIG. 8, Example 1 according to the present invention provided a discharge capacity restorability of 90% or more after an over-discharge test, and thus provided an excellent over-discharge preventing effect compared to Comparative Example 1.

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

PUM

No PUM Login to view more

Abstract

Disclosed is a cathode active material providing a cell performance that is not adversely affected by overdischarge, and a lithium secondary cell using the same. More particularly, the cathode active material for a lithium secondary cell comprises a lithium-transition metal oxide capable of lithium ion intercalation/deintercalation, wherein the cathode active material further comprises a lithium manganese oxide having a layered structure represented by the following formula 1 as an additive:[formula 1] LiMxMn1-x02 wherein, x is a number satisfying 0.05 x<0.5, and M is at least one metal selected from the group consisting of Cr, Al, Ni, Mn and Co. The lithium manganese oxide of formula 1 used as an additive for a cathode active material of a lithium secondary cell provides lithium ions in such an amount as to compensate for an irreversible lithium ion-consuming reaction at an anode, or more, thereby providing a lithium secondary cell which is low in capacity loss by over-discharge.

Description

TECHNICAL FIELD [0001] The present invention relates to a lithium secondary cell, the capacity of which is not significantly reduced after over-discharge and the capacity restorability of which after over-discharge is excellent, and more particularly, to a cathode active material comprising a lithium manganese oxide (LiMxMn1-xO2) having a layered structure as a cathode additive for improving over-discharge property, and a lithium secondary cell obtained by using the same. BACKGROUND ART [0002] Recently, as mobile communication industries and information electronic industries progress in various technologies, a light-weight lithium secondary cell having a high capacity is increasingly in demand. However, a lithium secondary cell may ignite and explode due to extreme heat emission, when it is over-charged or is in a short circuit state. Moreover, when a lithium secondary cell is over-discharged below a normal voltage range, its capacity is rapidly reduced so that it may not be used an...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

Application Information

Patent Timeline
no application Login to view more
IPC IPC(8): H01M4/48H01M4/50H01M4/52H01M4/505H01M4/04H01M4/131H01M4/36H01M4/485H01M4/525H01M6/16H01M10/052H01M10/0525H01M10/36
CPCH01M4/0445H01M4/131H01M4/364H01M4/485Y02E60/122H01M4/525H01M10/0525H01M2300/004H01M4/505Y02E60/10H01M4/48H01M10/052
Inventor LEE, JAE HYUNJANG, MIN CHULRYU, DUK HYUNJEONG, JUN YONGLEE, HAN HOAHN, SOON HO
Owner LG CHEM LTD
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Try Eureka
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap